In response to various injuries and conditions surgeons often find it necessary to separate or remove tissue from a patient. In some procedures it is desirable that tissue does not grow onto or adhere to other tissue during healing. Decompressive craniectomy is an example of such a case. This is a neurosurgical procedure in which part of the skull is removed to allow a swelling brain room to expand. It is performed on patients that have incurred a traumatic brain injury (TBI) such as following a car accident or a fall or in patients that have suffered a stroke.
When a neurosurgeon performs a decompressive craniectomy, part of the skull is removed and either a) stored in the patient's abdomen b) stored in a bone fridge or c) discarded.
Typically for a TBI, a 10-13 cm round piece of bone is removed. The surgeon will cut along the hair line through the skin down to the bone and peel the ‘skin flap’ back. The surgeon will then remove bone (craniectomy) and not disturb the underlying layer of tissue, known as the dura mater.
The dura mater or dura is the outermost of the three layers of the meninges surrounding the brain and spinal cord. The other two meningeal layers are the pia mater and the arachnoid mater. The dura surrounds the brain and the spinal cord and is responsible for keeping in the cerebrospinal fluid. The bone is removed and the skin and periosteum (membrane covering the bone) is sutured back up and the patient is generally sedated in ICU to allow the brain to swell. A patient can then leave the hospital and function mindful of the area in their brain unprotected by bone.
The patient can return for surgery to restore the cranial vault in 6 weeks to 2 years. During this time, the dura will adhere and scar to the subcutaneous tissue.
To repair the cranium, the surgeon needs to re-open the same wound, and carefully separate the dura from the skin and subcutaneous tissue because the bone or implant is usually placed between these layers. This generally takes 45-60 minutes and can cause the dura to be nicked or torn.
While some surgeons improvise by using plastic bags and other ad hoc measures to minimize tissue adhesion, there are some basic flat silicone sheets, such as those by Bentec Medical, on the market which may be used. Seprafilm® Adhesion Barrier (membrane) is an example of a basic flat sheet. This product is a sterile, bioresorbable, translucent adhesion barrier. Seprafilm Adhesion Barrier is indicated for use in patients undergoing abdominal or pelvic laparotomy as an adjunct intended to reduce the incidence, extent and severity of postoperative adhesions between the abdominal wall and the underlying viscera such as omentum, small bowel, bladder, and stomach, and between the uterus and surrounding structures such as tubes and ovaries, large bowel, and bladder.
Perthese® by Mentor is yet another example of silicone sheeting that is flexible. This is a translucent silicone elastomer sheeting material designed for medical and laboratory applications. It is made from an enhanced tear resistant elastomer that consists of dimethyl and methyl vinyl siloxane copolymers which are available as non-reinforced, reinforced and non reinforced extra firm varieties.
GORE PRECLUDE® PDX Dura Substitute is also available. This product is a flat sheet of opaque white material composed of PTFE (polytetrafluoroethylene) and is indicated for use as a temporary or permanent prosthesis for repair of dura mater during neurosurgery. GORE PRECLUDE® PDX Dura Substitute is for staged procedures and those that may require re-operation, such as, decompressive craniectomies, brain electrode mapping for seizure disorders, recurrent brain and spinal tumors. As well known in the art, sheets made of a medical grade flexible silicone film or a medical grade flexible PTFE film are inherently non-adherent to tissue.
The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art.